Many real world systems need to be controlled by predicting events and using those predictions to adjust equipment and mechanisms of the system. For example, in order to control online information retrieval systems, online advertising systems, manufacturing plant control systems, credit card fraud detection systems, email spam detection systems and many others. Often features describing the events to be predicted are clustered hierarchically. For example, features describing events such as childhood illnesses may be clustered by families which in turn are clustered into communities. However, existing systems for predicting events and using those predictions to control systems are not easily able to take into account knowledge about hierarchical event features so that it is exploited fully and in a simple and efficient manner.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known prediction and control systems.